Ok, then what is "vda" its size is 160Gb. I think its an "Unallocated space" Which we can extend it via disk manager in windows

So what I understood is I need to find a way to extend the size of "vda" so anyone can help me with this?

Unfortunately I don't have any words of wisdom to share when it comes to mounting an additional add-on disk with DigitalOcean. It's on the list of things to figure out, but so far we don't have a solution at present.

When you install the template initially you will need to use Windows Disk Management to expand the "C:" partition to cover the entire allocated virtual disk.